Which is the best vaccine?

Author: Giles Coghlan | Category: News

Shot in the arm

The short answer that is being encouraged by Gov't's is this: 'whichever one you can get'. One of the issues that Governments are facing that multiple vaccine options may mean that some are waiting for the 'better' vaccine to become available. So, which one is the 'best'?

It comes down to efficacy 

What is efficacy? if a vaccine has a 70% efficacy rate it means there is a 70% reduction in chance of an immunised person becoming ill vs a non-immunised person.

Efficacy on different levels

The 'efficacy' measurement can also be applied to different questions. So, for example, some vaccines appears to have a 100% efficacy rate in averting hospitalisation and death. Pretty useful.

So, what's the current range of efficacy data?

For vaccines that prevent COVID-19 case the two leaders are Pfizer and BioNTech:

  • Pfizer Inc:95%
  • BioNtech SE: 94%
  • Astrazeneca: 66.7%
  • Novavax: 89.3%
  • Johnson & Johnson: 66.9%
  • Chinese, India and Russian vaccines: Efficacy range from 50% to 91%. See table from Bloomberg below:

Shot in the arm

How reliable are the 'efficacy' levels

Hard to say as the different studies had different selection criteria. Where some sick patients allowed to take part in the trial l(like those with underlying health conditions) or where only 'healthy' individuals selected for the trials? When was the 'efficacy' result gathered as vaccines take time to develop. What exact symptoms were being monitored? What exactly constitutes a severe Covid-19 case. You see the point. The trials were not all conducted the same way. Also, a serious response to COVID-19 is comparatively infrequent, so a smaller pool makes it harder to assess. Especially as there trials are understandably being pushed through at a much quicker speed than normal.


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